This study seeks to determine whether maintenance of negative iron balance by chronic subcutaneous administration of desferrioxamine (DF) in a group of children between 5 and 27 years of age with transfusion dependent homoxygous beta-thalassemia: Prevents progression or reverses abnormalities in cardiac or endocrine function caused by hemosiderosis; has toxic consequences; continues to be effective without significant tachyphylaxis. During the next year, nine patients maintained on a "hypertransfusion" program will be treated with 1.0 - 2.0 gm of DF administered as an 8-12 hour daily subcutaneous infusion. Non-invasive cardiac and endocrine studies are repeated semiannually. Twenty-four urinary iron excretion is measured in each patient at 3-4 month intervals. Iron intake is estimated on the basis of the ml of RBC transfused. Using these two values, iron balance can be calculated. Provocative testing will be repeated on patients who had abnormal baseline studies. In addition, tree patients who are presently showing early pubertal changes will be studied with acute LHRH infusions. Since a number of our patients have had a number of these studies repeated over a five-year period, we may be able to assess a slowing or stabilization of endocrine changes. Cardiac evaluation will consist of Holter monitoring every 6 months to detect the presence of significant cardiac dysrythmias. Follow-up evaluation of left ventricular function will be performed each year by echocardiography and radionuclide angiocardography and will include thallium scans to evaluate any myocardial perfusion defects. Exercise evaluation of left ventricular function by radionuclide angiocardiography will be considered in these patients as well.